Teams chat retention policy

Hi. I am testing Teams chat retention policies before deploying to live tenant. The aim of the policy is to delete Teams 1:1 chat messages after a certain period of time. For testing I have it set to 1 day. The goal would be to deploy this policy to some users and not others in my tenant. In testing I have user A and B who are part of a retention deletion policy to delete Teams chat history after 1 day. User C and D are not part of this policy.

However when the policy is applied the chat history for users C & D are also delete for any conversation 1:1, meeting or group chats they have had with users A or B. This is problematic as I want to be able to retain the chat history for users that are not part of the policy.

Depending on what you read online you are either able to retain chat history for users that are not part of the policy as a copy of the chat is stored in a hidden folder in their mailbox or it cant be done as once the Azure chat service in the backend get the delete command from the retention policy it will delete the chat history for all users in the conversation even if they are not part of the policy. 

So my question is, is it possible to retain chat history for a user who has had Teams chats with a user who is part of a retention deletion policy? And can it remain in their list of chats in the Teams client of web app?

Thanks

Mark